This invention relates, in general, to magnetic bubble domain memories, and more particularly, to a magnetic bubble domain memory having an improved replicator.
Magnetic bubble domain memories are becoming well known, and more recently, have been called magnetic bubble memories or just plain bubble memories. Bubble propagation in such memories is accomplished by creating a changing pattern of localized magnetic field gradients. The memories are arranged to have circulating storage loops which are commonly called minor loops. A memory will have a plurality of minor loops which are connected to a major loop. A schematic representation of the major and minor loops is shown in A. H. Bobeck U.S. Pat. No. 4,355,373. Typically bubble memories will have a replicator located between each of the minor loops and the major loop. There are two principal methods of bubble replication. The most widely used replication schemes involve the use of a pulsed conductor loop with a permalloy pattern to split a bubble into two bubbles. In this type of replicator the bubble is elongated and then severed into two bubbles by applying a control current pulse to provide a repulsive magnetic force to the middle of the elongated bubble. The other type of field access bubble replicator uses permalloy patterns only and does not require a control current pulse. This second type of replicator is commonly called a passive bubble replicator. An example of a magnetic bubble passive replicator is disclosed in Collins et al U.S. Pat. No. 4,415,987.
It has been noted that in magnetic bubble memories having the current assisted bubble splitters, problems have been exhibited particularly under conditions of dense bubble population. In other words, when the memory was loaded with the dense population of bubble domains occasionally one of the bubble domains would collapse. The bubble domain would collapse during the high bias margin operational limit. Further investigation determined that under the high bias operational limit the bubble domain would collapse during propagation around the U-turn under conditions of dense bubble population and was due to bubble-to-bubble interaction effects in the U-turn area. The U-turn area forms part of the block replicate gate.
Accordingly, it is an object of the present invention to provide an improved replicator for a magnetic bubble domain memory.
Yet another object of the present invention is to provide an improvement of operating bias margins under conditions of full bubble loading.
Yet a further object of the present invention is to provide a block replicate gate having a notch formed in one leg of the replicator.
Yet a further object of the present invention is to provide a magnetic bubble memory having improved bias margin for propagation of the bubble around the U-turn and also resulting in a memory having extended temperature capabilities.